The present invention relates to an optical apparatus and image sensing apparatus which form an object image on a solid-state image sensing element through a photographing optical member and, more particularly, to an optical apparatus and image sensing apparatus which sense an object image by using a solid-state image sensing element.
A solid-state image sensing element such as a CCD is used for an image sensing apparatus such as an electronic still camera or video camera. This solid-state image sensing element is sealed in a bare chip, a ceramic package, or the like. The image sensing surface of the solid-state image sensing element is exposed on the upper surface of this package, and a plurality of terminals such as an output terminal for outputting signals accumulated in the solid-state image sensing element and an input terminal for inputting a timing pulse or the like are arranged on the lower surface of the package. These terminals are soldered to corresponding electrical connection portions formed on a board. By soldering the terminals to the board, the solid-state image sensing element is mounted on the board.
Generally, an optical apparatus using a solid-state image sensing element has a zoom lens mechanism to obtain a desired photographing range.
A method of mounting this solid-state image sensing element will be described in detail below with reference to FIG. 30. FIG. 30 is a perspective view showing a method of mounting a conventional solid-state image sensing element.
When a solid-state image sensing element sealed in a package is to be mounted on a board, the solid-state image sensing element is mounted with its lower surface opposing the upper surface of the board, and the terminals arranged on the lower surface of the solid-state image sensing element are soldered to the corresponding lands on the upper surface of the board, as shown in FIG. 30. The board on which this solid-state image sensing element is mounted is connected, through a wiring means such as lead wires or a flexible board, to a board on which a signal processing IC and the like are mounted.
The image sensing apparatus using the above solid-state image sensing element will be described next with reference to FIG. 31. FIG. 31 is a longitudinal sectional view showing the arrangement of the image sensing apparatus using the solid-state image sensing element.
As shown in FIG. 31, the image sensing apparatus includes a plurality of lens groups constituted by a first lens group 101a, a second lens group 101b, a third lens group 101c, and a fourth lens group 101d. The second and fourth lens groups 101b and 101d are moved along the optical axis within predetermined ranges. The second lens group 101b is moved to perform a zooming operation. The fourth lens group 101d is moved to perform focus adjustment.
An optical low-pass filter 102 and a solid-state image sensing element 103 such as a CCD are sequentially arranged on the optical axis behind the fourth lens group 101d. 
The first lens group 101a, the third lens group 101c, the optical low-pass filter 102, the solid-state image sensing element 103, and the like are held in a housing 104.
The second lens group 101b is held in an optical holding member 105. The optical holding member 105 is supported to be movable along the optical axis on a guide pin 106 and a threaded member 107 which extend parallel along the optical axis. Each end portion of the guide pin 106 is supported on the housing 104.
The threaded member 107 has a threaded portion to be engaged with the optical holding member 105. Each end portion of the threaded member 107 is rotatably supported on the housing 104. A driving force from a stepping motor 110 is transferred to the threaded member 107 through a gear group 101. When the threaded member 107 is rotated by the driving force from the stepping motor 110, the optical holding member 105 is guided by the guide pin 106 and moved along the optical axis upon rotation of the threaded member 107. By moving the optical holding member 105, a zooming operation using the second lens group 101b is performed. The play between the threaded member 107 and the optical holding member 105 is removed by a biasing spring 108 and a biasing member 109.
Similar to the second lens group 101b, the fourth lens group 101d is supported in an optical holding member 116. The optical holding member 116 is supported to be movable along the optical axis on a guide pin 117 and a threaded member 113 which extend parallel along the optical axis. Each end portion of the guide pin 117 is supported on the housing 104.
The threaded member 113 has a threaded portion to be engaged with the optical holding member 116. One end portion of the threaded member 113 is rotatably supported on the housing 104. The other end portion of the threaded member 113 is rotatably supported on the housing 104 and directly connected to the output shaft of a stepping motor 112. When the threaded member 113 is rotated by a driving force from the stepping motor 112, the optical holding member 116 is guided by the guide pin 117 and moved along the optical axis upon rotation of the threaded member 113. By moving the optical holding member 116, focus adjustment using the fourth lens group 101d is performed. The play between the threaded member 113 and the optical holding member 116 is removed by the biasing spring 108 and the biasing member 109.
The moving positions of the second and fourth lens groups 101b and 101d, i.e., the moving positions of the optical holding members 105 and 116, are detected by position detection means (not shown). The detection amounts are used to control a zooming operation and a focus adjusting operation.
A stop 114 is disposed between the second lens group 101b and the third lens group 101c. The aperture of the stop 114 is adjusted by a driving force from a motor 115. The exposure amount is adjusted by this adjustment of the aperture of the stop 114.
The housing 104 serves both as a means for shielding each lens group and the solid-state image sensing element 103 against light and as a means for shielding them against electromagnetism.
With the recent advances in semiconductor chips such as memories and microcomputers, portable information devices have spread. Efforts have been made to further miniaturize such devices and improve their performance. Portability is a requirement for such portable information devices. Regarding the forms of the devices, a low profile is especially required.
These portable information devices include an optical apparatus for photographing an object image, information equipment including this optical apparatus, and the like. In order to obtain a low-profile optical apparatus, the overall thickness of the apparatus including a photographing optical system (a system constituted by, e.g., the lens groups, the stop, and the solid-state image sensing element in FIG. 31) and a mechanical system (a system constituted by, e.g., the gears and the motors which drive the lens groups, the motor which drives the stop, and the like in FIG. 31) must be decreased.
In general, in the conventional optical apparatus, however, since the optical holding member 105 included in the mechanical system is axially supported to be symmetrical with the optical axis, the outer size of the housing 104 becomes large as compared with the lens system. In addition, since the motor and the like are disposed outside the housing 104, the overall outer size of the apparatus further increases. It is therefore very difficult to decrease the size of the apparatus in a direction perpendicular to the optical axis, i.e., to attain a decrease in thickness in the direction perpendicular to the optical axis.
The first to fourth lens groups 101a to 101d, the optical low-pass filter 102, the solid-state image sensing element 103, and the like are held in the housing 104, and the motor 115 for driving the stop 114, the stepping motor 110 for driving the second lens group 101b, the stepping motor 112 for driving the fourth lens group 101d, and the like are held outside the housing 104. For this reason, the housing 104 has a three-dimensionally complicated shape. In addition, a light-shielding means for shielding each lens group and the solid-state image sensing element 103 against light or a shielding means for shielding each lens group and the solid-state image sensing element 103 against electromagnetism must be formed by using this housing 104 having the complicated shape. With the light-shielding means or the shielding means, a decrease in the thickness of the apparatus is more difficult to attain.
As described above, in the method of mounting a conventional solid-state image sensing element on a signal processing board on which a signal processing IC and the like are mounted, the solid-state image sensing element is mounted on the board, and the board is then connected to the signal processing board, on which the signal processing IC and the like are mounted, through lead wires or a flexible board. Such a mounting method requires many steps, resulting in a complicated assembly operation.
Since the board on which the solid-state image sensing element is mounted is interposed between the solid-state image sensing element and the signal processing board, the signal processing board, on which the solid-state image sensing element is mounted, increases in size in the direction of thickness. It is therefore difficult to decrease the thickness of the photographing optical system, and hence it is very difficult to obtain a low-profile image sensing apparatus.
In addition, in the conventional optical apparatus, for example, since the optical holding member 105 is supported on the guide pin 106 and the threaded member 107 to be symmetrical about the optical axis, the outer diameter of the housing 104 becomes larger as compared with the outer diameter of the second lens group 101b. In addition, the motor 115 for driving the stop 114, the stepping motor 110 for driving the second lens group 101b, the stepping motor 112 for driving the fourth lens group 101d, and the like are held outside the housing 104. For this reason, it is very difficult to decrease the dimension in a direction perpendicular to the optical axis, i.e., the thickness in the direction perpendicular to the optical axis. That is, it is very difficult to obtain a low-profile apparatus.
Furthermore, in the conventional optical apparatus, the first to fourth lens groups 101a to 101d, the optical low-pass filter 102, the solid-state image sensing element 103, and the like are held in the housing 104, and the motor 115 for driving the stop 114, the stepping motor 110 for driving the second lens group 101b, the stepping motor 112 for driving the fourth lens group 101d, and the like are held outside the housing 104. That is, the housing 104 has a three-dimensionally complicated shape. For this reason, the cost in manufacturing a housing mold generally using a plastic mold increases. In addition, sink marks, warpage, and the like are caused by partial heat shrinkage of the housing 104, and hence it is difficult to manufacture the housing 104 with high dimensional precision. Consequently, it is difficult to perform positioning of each lens group with respect to the solid-state image sensing element 103. Deterioration in image quality such as blurring of photographed images is caused by a slight offset between each lens group and the solid-state image sensing element 103.
Generally, the optical holding members 105 included in the mechanical system is axially supported to be symmetrical about the optical axis. For this reason, the outer size of the housing 104 is large as compared with the lens system. In addition, since the motor and the like are disposed outside the housing 104, the overall outer size of the apparatus further increases. It is therefore very difficult to decrease the size of the apparatus in a direction perpendicular to the optical axis, i.e., the thickness of the apparatus in the direction perpendicular to the optical axis.
In the conventional optical apparatus, the first to fourth lens groups 101a to 101d, the optical low-pass filter 102, the solid-state image sensing element 103, and the like are held in the housing 104, and the motor 115 for driving the stop 114, the stepping motor 110 for driving the second lens group 101b, the stepping motor 112 for driving the fourth lens group 101d, and the like are held outside the housing 104. That is, the housing 104 has a three-dimensionally complicated shape. For this reason, the cost in manufacturing a housing mold generally using a plastic mold increases. In addition, sink marks, warpage, and the like are caused by partial heat shrinkage of the housing 104, and hence it is difficult to manufacture the housing 104 with high dimensional precision. Consequently, it is difficult to perform positioning of each lens group with respect to the solid-state image sensing element 103, positioning of each holding member, and the like. For this reason, each lens group may tilts or lenses may swing during movement of each lens group. This may cause blurring or fluctuations of photographed images.
An electric circuit board on which an image sensing element drive circuit for driving the solid-state image sensing element included in the photographing optical system and actuator drive circuits for driving the motors included in the mechanical system are mounted must be connected to the solid-state image sensing element and the motor through lead wires, a flexible board, or the like. Such a mounting method requires many steps, resulting in a complicated assembly operation.
Since the optical holding member 105 included in the mechanical system is generally supported to be symmetrical about the optical axis, the outer size of the housing 104 is large as compared with the lens system. Since the motors and the like are disposed outside the housing 104, the overall outer size of the apparatus further increases. It is, therefore, very difficult to decrease the dimension of the apparatus in the direction perpendicular to the optical axis, i.e., the thickness in the direction perpendicular to the optical axis.
In addition, since mechanical and electric parts must be mounted in various directions in assembling the apparatus, a cumbersome assembly operation is required, resulting in an increase in cost.
It is an object of the present invention to provide an optical apparatus which has good assembly performance, can suppress an increase in cost, and can decrease the thickness.
It is another object of the present invention to provide an optical apparatus which can decrease the overall thickness of the apparatus, and prevents a light-shielding means from interfering with a decrease in the thickness of the apparatus.
It is still another object of the present invention to provide an optical apparatus which can decrease the overall thickness of the apparatus, and prevents a shielding means from interfering with a decrease in the thickness of the apparatus.
It is still another object of the present invention to provide an optical apparatus which can decrease the overall thickness of the apparatus, and prevents light-shielding and shielding means from interfering with a decrease in the thickness of the apparatus.
It is still another object of the present invention to provide an image sensing apparatus which can facilitate an assembly process, and can decrease the thickness.
It is still another object of the present invention to provide an optical apparatus which can easily decrease the overall thickness of the apparatus.
It is still another object of the present invention to provide an optical apparatus which can prevent image quality from being deteriorated by inaccuracy of relative positioning between each optical member and a solid-state image sensing element included in a photographing optical system, and can decrease the overall thickness of the apparatus.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.